Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.617
Filtrar
1.
Molecules ; 26(6)2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33809377

RESUMO

Muscle fatigue is induced by an acute or chronic physical performance inability after excessive physical activity often associated with lactate accumulation, the end-product of glycolysis. In this study, the water-extracted roots of Sanguisorba officinalis L., a herbal medicine traditionally used for inflammation and diarrhea, reduced the activities of lactate dehydrogenase A (LDHA) in in vitro enzyme assay myoblast C2C12 cells and murine muscle tissue. Physical performance measured by a treadmill test was improved in the S. officinalis-administrated group. The analysis of mouse serum and tissues showed significant changes in lactate levels. Among the proteins related to energy metabolism-related physical performance, phosphorylated-AMP-activated protein kinase alpha (AMPKα) and peroxisome proliferator-activated receptor-coactivator-1 alpha (PGC-1α) levels were enhanced, whereas the amount of LDHA was suppressed. Therefore, S. officinalis might be a candidate for improving physical performance via inhibiting LDHA and glycolysis.


Assuntos
Lactato Desidrogenase 5/antagonistas & inibidores , Desempenho Físico Funcional , Extratos Vegetais/administração & dosagem , Plantas Medicinais/química , Sanguisorba/química , Proteínas Quinases Ativadas por AMP/metabolismo , Administração Oral , Animais , Linhagem Celular , Teste de Esforço , Glicólise/efeitos dos fármacos , Ácido Láctico/metabolismo , Masculino , Medicina Tradicional Coreana , Camundongos , Camundongos Endogâmicos C57BL , Mioblastos Esqueléticos/efeitos dos fármacos , Mioblastos Esqueléticos/enzimologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Resistência Física/efeitos dos fármacos , Compostos Fitoquímicos/administração & dosagem , Compostos Fitoquímicos/química , Fitoterapia , Extratos Vegetais/química
2.
J Int Soc Sports Nutr ; 18(1): 25, 2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33781269

RESUMO

PURPOSE: The main goal of this study was to assess the acute effects of 3 and 6 mg of caffeine intake per kg of body mass (b.m.) on maximal strength and strength-endurance in women habituated to caffeine. METHODS: Twenty-one healthy resistance-trained female students (23.0 ± 0.9 years, body mass: 59.0 ± 6.6 kg), with a daily caffeine intake of 5.8 ± 2.6 mg/kg/b.m. participated in a randomized, crossover, double-blind design. Each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 3 mg/kg/b.m. (CAF-3) and 6 mg/kg/b.m. (CAF-6) of caffeine. In each experimental session, the participants underwent a 1RM test and a strength-endurance test at 50 %1RM in the bench press exercise. Maximal load was measured in the 1RM test and the time under tension, number of preformed repetitions, power output and bar velocity were registered in the strength-endurance test. RESULTS: The one-way ANOVA showed a main effect of caffeine on 1RM bench press performance (F = 14.74; p < 0.01). In comparison to the PLAC (40.48 ± 9.21 kg), CAF-3 (41.68 ± 8.98 kg; p = 0.01) and CAF-6 (42.98 ± 8.79 kg; p < 0.01) increased 1RM bench press test results. There was also a significant increase in 1RM for CAF-6 when compared to CAF-3 (p < 0.01). There was a main effect of caffeine on time under tension during the strength-endurance test (F = 13.09; p < 0.01). In comparison to the PLAC (53.52 ± 11.44 s), CAF-6 (61.76 ± 15.39 s; p < 0.01) significantly increased the time under tension during the maximal strength-endurance test. CONCLUSION: An acute dose of 3-to-6 mg/kg/b.m. of caffeine improves maximum strength. However, these doses of caffeine had minimal ergogenic effect on strength-endurance performance in women habituated to caffeine.


Assuntos
Cafeína/administração & dosagem , Força Muscular/efeitos dos fármacos , Substâncias para Melhoria do Desempenho/administração & dosagem , Resistência Física/efeitos dos fármacos , Administração Oral , Estudos Cross-Over , Método Duplo-Cego , Comportamento de Ingestão de Líquido , Feminino , Humanos , Adulto Jovem
3.
Food Chem ; 353: 129463, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33743428

RESUMO

Codium fragile (CF) is a type of green algae consumed as kimchi in Asia. UPLC-QTOF-MS/MS analysis showed that CF contain lysophosphatidyl choline, canthaxanthin, retinoic acid, α-tocopherol, and unsaturated fatty acids, which reportedly improve skeletal muscle health. However, the effect of CF on skeletal muscle mass and function remains to be elucidated. In mice fed with CF extracts, exercise endurance and muscle weight increased. CF extracts enhanced protein synthesis and myogenic differentiation through the mTORC1 pathway. CF extracts also promoted oxidative muscle fiber formation and mitochondrial biogenesis through the PGC-1α-related signaling pathway. Upregulation of PGC-1α by CF extracts was abolished by EX527 SIRT1 inhibitor treatment. Changed signaling molecules in the CF extracts were partially regulated by canthaxanthin, a new compound in CF extracts, suggesting that canthaxanthin contribute synergistically to the effect of CF extracts. Therefore, CF is a potential food source for sport nutrition or prevention of sarcopenia.


Assuntos
Clorófitas/química , Músculo Esquelético/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Animais , Cantaxantina/análise , Carbazóis/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Músculo Esquelético/fisiologia , Tamanho do Órgão/efeitos dos fármacos , Biogênese de Organelas , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Condicionamento Físico Animal/fisiologia , Resistência Física/fisiologia , Extratos Vegetais/análise , Alga Marinha/química , Transdução de Sinais/efeitos dos fármacos , Espectrometria de Massas em Tandem , Regulação para Cima/efeitos dos fármacos
4.
Food Funct ; 12(3): 1338-1348, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33448266

RESUMO

Rice is a staple food in Korea. The protein in rice reportedly contains higher levels of branched-chain amino acids (BCAAs) than proteins in other grains. Taking BCAAs during exercise can reduce muscle fatigue by reducing muscle glycogen depletion. However, there are limited studies reporting the anti-fatigue effect of rice protein. We investigate the muscular endurance and anti-fatigue effects of the protein hydrolysate of rice syrup meal in mouse models. BALB/C mice were divided into the following groups: control (CON), low and high dose rice syrup meal (RL: 1.5 g kg-1; RH: 3.0 g kg-1), and low and high dose protein hydrolysate of rice syrup meal (PL: 1.5 g kg-1; PH: 3.0 g kg-1). The total activity during a forced swimming test was analyzed by a behavioral assay. The mutual relationship between the anti-fatigue activity and energy metabolism was assessed by biochemical, enzyme activity, and gene expression analyses. The protein hydrolysate of rice syrup meal contained 32.18 mg g-1 BCAAs, such as leucine, isoleucine, and valine, and its BCAA ratio (2.5 : 1.0 : 1.4) was considered effective for endurance exercise. Furthermore, PH administration significantly increased the change in the maximum swimming duration by 4.2 min (3.77 ± 0.74 min) compared to that of the CON group (-0.42 ± 0.55 min, p < 0.01). The PH group showed significantly different changes in the blood glucose and lactate levels compared with the CON group; similarly, the aspartate amino transferase and alanine amino transferase levels were significantly lower in the protein hydrolysate of rice syrup meal group than the CON group (p < 0.001 and p < 0.01, respectively). The protein hydrolysate of rice syrup meal-mediated improvement of endurance performance was accompanied by an increased in adenosine triphosphate content in the muscle and decreased reactive oxygen species accumulation in the liver. In addition, mRNA and protein levels of phospho-AMP activated protein kinase (p-AMPK)/AMPK and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), the major energy-related factors of protein hydrolysate of rice syrup meal, were significantly increased. The protein hydrolysate of rice syrup meal can be utilized as an efficacious natural resource for its muscular-endurance-enhancing and anti-fatigue effects.


Assuntos
Ração Animal/análise , Resistência Física/efeitos dos fármacos , Hidrolisados de Proteína/farmacologia , Animais , Dieta , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Oryza/química , Condicionamento Físico Animal , Hidrolisados de Proteína/administração & dosagem , Hidrolisados de Proteína/química , Natação
5.
Int J Sports Med ; 42(2): 147-152, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32851636

RESUMO

Training volume is one of the critical variables required to promote resistance training benefits (e. g., hypertrophy, muscular strength). Thus, strategies to improve training volume are required. We tested the hypothesis that there is an increase in performance and reduction in the rate of perceived exertion in strength training with caffeine supplementation, carbohydrate mouth rinse, and a synergistic effect of caffeine supplementation plus carbohydrate mouth rinse. We recruited 29 physically active women: 24±4 years, 60.0±7.9 kg, 161.0±6.0 cm. This study was a double-blind, randomized, placebo-controlled, and crossover one. The subjects performed all sessions of strength training under different conditions: caffeine (6.5 mg·kg-1 body mass); carbohydrate (6 g of maltodextrin rinsed for 10 s); caffeine plus carbohydrate; or placebo. We applied the ANOVA for repeated measures through the null-hypothesis statistical test, and the Bayes factors analyses approach. The subjects showed significant improvement in the total repetitions (P<0.01; BF10 ~99%) for both lower and upper limb exercises in all conditions compared to placebo without difference among interventions. The rate of perceived exertion (P>0.05) did not differ among interventions. However, BF10 analyses showed a higher probability of lower RPE for CAF intervention. We conclude that either caffeine supplementation or carbohydrate mouth rinse can improve performance in resistance training. There is no additional effect of caffeine plus carbohydrate.


Assuntos
Desempenho Atlético/fisiologia , Cafeína/administração & dosagem , Carboidratos da Dieta/administração & dosagem , Suplementos Nutricionais , Antissépticos Bucais/farmacologia , Resistência Física/efeitos dos fármacos , Treinamento de Força , Adulto , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Adulto Jovem
6.
J Sci Med Sport ; 24(4): 412-417, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33162329

RESUMO

OBJECTIVES: To investigate the effects of acute branched-chain amino acid (BCAA) supplementation on cycling performance and neuromuscular fatigue during a prolonged, self-paced cycling time-trial. DESIGN: Randomised double-blind counterbalanced crossover. METHODS: Eighteen recreationally active men (mean±SD; age: 24.7±4.8 years old; body-weight, BW: 67.1±6.1kg; height: 171.7±4.9cm) performed a cycling time-trial on an electromagnetically-braked cycle ergometer. Participants were instructed to complete the individualised total work in the shortest time possible, while ingesting either BCAAs (pre-exercise: 0.084gkg-1 BW; during exercise: 0.056gkg-1h-1) or a non-caloric placebo solution. Rating of perceived exertion, power, cadence and heart rate were recorded throughout, while maximal voluntary contraction, muscle voluntary activation level and electrically evoked torque using single and doublet stimulations were assessed at baseline, immediately post-exercise and 20-min post-exercise. RESULTS: Supplementation with BCAA reduced (287.9±549.7s; p=0.04) time-to-completion and ratings of perceived exertion (p≤0.01), while concomitantly increasing heart rate (p=0.02). There were no between-group differences (BCAA vs placebo) in any of the neuromuscular parameters, but significant decreases (All p≤0.01) in maximal voluntary contraction, muscle voluntary activation level and electrically evoked torque (single and doublet stimulations) were recorded immediately following the trial, and these did not recover to pre-exercise values by the 20min recovery time-point. CONCLUSIONS: Compared to a non-caloric placebo, acute BCAA supplementation significantly improved performance in cycling time-trial among recreationally active individuals without any notable changes in either central or peripheral factors. This improved performance with acute BCAA supplementation was associated with a reduced rating of perceived exertion.


Assuntos
Aminoácidos de Cadeia Ramificada/administração & dosagem , Ciclismo/fisiologia , Suplementos Nutricionais , Fadiga Muscular/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Esforço Físico/efeitos dos fármacos , Adulto , Estudos Cross-Over , Método Duplo-Cego , Humanos , Masculino , Adulto Jovem
7.
Eur J Sport Sci ; 21(1): 77-83, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31994989

RESUMO

Citrulline-malate (CM) purportedly increases exercise performance through increased nitric oxide production. The effects of CM on muscular strength performance are well-documented; however, the benefits of CM on aerobic and anaerobic biking performance are not well researched. Therefore, the present investigation examined the acute CM supplementation effects on aerobic and anaerobic cycling performance in recreationally active males. Methods: 28 recreationally active males (20.9 ± 2.8 years) completed randomized, double-blind, crossover trials consuming CM (12g dextrose + 8g CM) or a placebo (12g dextrose). Participants performed an aerobic cycling protocol (time-to-exhaustion [TTE]), followed by a subsequent 30-second Wingate cycling test, 60-minutes after supplement consumption. Results: Dependent t-tests showed no significant differences (p > 0.05) for TTE (PLA: 315.4 s ± 137.7 s; CM: 314.1 s ± 107.1 s) and Total Work Completed (TWC) (PLA: 74.7 ± 34.1 kilojoules (kJ); CM: 74.1 ± 26.4 kJ) during the aerobic cycling protocol. Dependent t-tests also showed no significant differences (p > 0.05) for mean watts (PLA: 586.1 ± 87.7 Watts (W); CM: 588.0 ± 93.0 W), peak watts (PLA: 773.0 ± 136.7 W; CM: 786.7 ± 133.0 W), and fatigue index (PLA: 12.9 ± 6.4 FI; CM: 14.3 ± 7.2 FI) during the Wingate protocol. Repeated-measures ANOVA results indicated a significant effect between each 5 s interval (p < 0.001), but no differences were observed between trials (p > 0.05). Conclusion: Acute CM supplementation in recreationally active males provides no ergogenic benefit in aerobic cycling performance followed by an anaerobic cycling test.


Assuntos
Ciclismo/fisiologia , Citrulina/análogos & derivados , Exercício Físico/fisiologia , Malatos/farmacologia , Óxido Nítrico/biossíntese , Substâncias para Melhoria do Desempenho/farmacologia , Análise de Variância , Desempenho Atlético/fisiologia , Citrulina/farmacologia , Estudos Cross-Over , Método Duplo-Cego , Glucose/administração & dosagem , Humanos , Masculino , Resistência Física/efeitos dos fármacos , Resistência Física/fisiologia , Edulcorantes/administração & dosagem , Adulto Jovem
9.
Nutrients ; 12(12)2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33333771

RESUMO

This study investigated the efficacy of ingesting an oral rehydration solution (DD) that has a high electrolyte concentration after exercise on fluid balance and cycling performance in comparison with a sports drink (SD) and water (WA). Nine healthy males aged 24 ± 2 years (mean ± SD), with peak oxygen uptake (VO2 peak) 55 ± 6 mL·kg-1·min-1 completed three experimental trials in a randomised manner ingesting WA, SD (carbohydrates: 62 g·L-1, sodium: 31 ± 3 mmol·L-1) or DD (carbohydrates: 33 g·L-1, sodium: 60 ± 3 mmol·L-1). On all trials, fluid was ingested during 75 min cycling at 65% VO2 peak (temperature: 30.4 ± 0.3 °C, relative humidity: 76 ± 1%, simulated wind speed: 8.0 ± 0.6 m·s-1) and during 2 h of recovery (temperature: 23.0 ± 1.0 °C, relative humidity: 67 ± 2%), with the total volume equivalent to 150% of sweat loss during the ride. A 45 min pre-load cycling time trial at a 65% VO2 peak followed by a 20 km time trial was conducted after a further 3 h of recovery. Fluid retention was higher with DD (30 ± 15%) than WA (-4 ± 19%; p < 0.001) and SD (10 ± 15%; p = 0.002). Mean ratings of palatability were similar among drinks (WA: 4.25 ± 2.60; SD: 5.61 ± 1.79; DD: 5.40 ± 1.58; p = 0.33). Although time trial performance was similar across all three trials (WA: 2365 ± 321 s; SD: 2252 ± 174 s; DD: 2268 ± 184 s; p = 0.65), the completion time was faster in eight participants with SD and seven participants with DD than with WA. Comparing SD with DD, completion time was reduced in five participants and increased in four participants. DD was more effective at restoring the fluid deficit during recovery from exercise than SD and WA without compromising the drink's palatability with increased sodium concentration. Most individuals demonstrated better endurance exercise time trial performance with DD and SD than with WA.


Assuntos
Ciclismo/fisiologia , Ingestão de Líquidos/fisiologia , Resistência Física/efeitos dos fármacos , Soluções para Reidratação/administração & dosagem , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Adulto , Água Potável/administração & dosagem , Bebidas Energéticas , Teste de Esforço , Voluntários Saudáveis , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Sódio/administração & dosagem , Fatores de Tempo , Adulto Jovem
10.
Int J Mol Sci ; 21(20)2020 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-33086540

RESUMO

(1) Background: Regular exercise induces physiological and morphological changes in the organisms, but excessive training loads may induce damage and impair recovery or muscle growth. The purpose of the study was to evaluate the impact of Silymarin (SM) consumption on endurance capacity, muscle/cardiac histological changes, bodyweight, and food intake in rats subjected to 60 min of regular exercise training (RET) five days per week. (2) Methods: Male Wistar rats were subjected to an eight-week RET treadmill program and were previously administered SM and vitamin C. Bodyweight and food consumption were measured and registered. The maximal endurance capacity (MEC) test was performed at weeks one and eight. After the last training session, the animals were sacrificed, and samples of quadriceps/gastrocnemius and cardiac tissue were obtained and process for histological analyzes. (3) Results: SM consumption improved muscle recovery, inflammation, and damaged tissue, and promoted hypertrophy, vascularization, and muscle fiber shape/appearance. MEC increased after eight weeks of RET in all trained groups; moreover, the SM-treated group was enhanced more than the group with vitamin C. There were no significant changes in bodyweight and in food and nutrient consumption along the study. (5) Conclusion: SM supplementation may enhance physical performance, recovery, and muscle hypertrophy during the eight-week RET program.


Assuntos
Peso Corporal , Suplementos Nutricionais , Comportamento Alimentar , Músculo Esquelético/patologia , Miocárdio/patologia , Condicionamento Físico Animal , Desempenho Físico Funcional , Silimarina/farmacologia , Animais , Ácido Ascórbico/farmacologia , Peso Corporal/efeitos dos fármacos , Masculino , Músculo Esquelético/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Ratos Wistar , Silimarina/química
11.
Med Sci Sports Exerc ; 52(11): 2437-2447, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33064413

RESUMO

INTRODUCTION: Nitric oxide (NO) precursor supplementation has been shown to increase NO bioavailability and can potentially improve vascular function and exercise performance. It remains unclear whether the combination of NO precursor supplementation and exercise training has synergic effects on exercise performance. This study aims to assess the effect of chronic nitrate and citrulline intake on exercise training adaptations in healthy young individuals. METHODS: In this randomized, double-bind trial, 24 healthy young (12 females) subjects performed vascular function assessment (blood pressure, pulse wave velocity, postischemia vasodilation, and cerebrovascular reactivity) and both local (submaximal isometric unilateral knee extension) and whole-body (incremental cycling) exercise tests to exhaustion before and after a 2-month exercise training program and daily intake of a placebo or a nitrate-rich salad and citrulline (N + C, 520 mg nitrate and 6 g citrulline) drink. Prefrontal cortex and quadriceps oxygenation was monitored continuously during exercise by near-infrared spectroscopy. RESULTS: N + C supplementation had no effect on vascular function and muscle and cerebral oxygenation during both local and whole-body exercise. N + C supplementation induced a significantly larger increase in maximal knee extensor strength (+5.1 ± 3.5 vs +0.2 ± 5.5 kg, P = 0.008) as well as a trend toward a larger increase in knee extensor endurance (+35.2 ± 26.1 vs +24.0 ± 10.4 contractions, P = 0.092) than placebo, but no effect on exercise training-induced maximal aerobic performance improvement. CONCLUSION: These results suggest that chronic nitrate and citrulline supplementation enhances the effect of exercise training on quadriceps muscle function in healthy active young individuals, but this does not translate into improved maximal aerobic performances.


Assuntos
Citrulina/administração & dosagem , Suplementos Nutricionais , Exercício Físico/fisiologia , Força Muscular/efeitos dos fármacos , Nitratos/administração & dosagem , Óxido Nítrico/metabolismo , Resistência Física/efeitos dos fármacos , Adaptação Fisiológica , Adulto , Método Duplo-Cego , Teste de Esforço , Feminino , Voluntários Saudáveis , Humanos , Masculino , Vasodilatação/efeitos dos fármacos , Adulto Jovem
12.
Med Sci Sports Exerc ; 52(10): 2250-2261, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32936597

RESUMO

Although over 100 studies and reviews have examined the ergogenic effects of dietary nitrate (NO3) supplementation in young, healthy men and women, it is unclear if participant and environmental factors modulate the well-described ergogenic effects-particularly relevant factors include biological sex, aerobic fitness, and fraction of inspired oxygen (FiO2) during exercise. To address this limitation, the literature was systematically reviewed for randomized, crossover, placebo-controlled studies reporting exercise performance outcome metrics with NO3 supplementation in young, healthy adults. Of the 2033 articles identified, 80 were eligible for inclusion in the meta-analysis. Random-effects meta-analysis demonstrated that exercise performance improved with NO3 supplementation compared with placebo (d = 0.174; 95% confidence interval (CI), 0.120-0.229; P < 0.001). Subgroup analyses conducted on biological sex, aerobic fitness, and FiO2 demonstrated that the ergogenic effect of NO3 supplementation was as follows: 1) not observed in studies with only women (n = 6; d = 0.116; 95% CI, -0.126 to 0.358; P = 0.347), 2) not observed in well-trained endurance athletes (≥65 mL·kg·min; n = 26; d = 0.021; 95% CI, -0.103 to 0.144; P = 0.745), and 3) not modulated by FiO2 (hypoxia vs normoxia). Together, the meta-analyses demonstrated a clear ergogenic effect of NO3 supplementation in recreationally active, young, healthy men across different exercise paradigms and NO3 supplementation parameters; however, the effect size of NO3 supplementation was objectively small (d = 0.174). NO3 supplementation has more limited utility as an ergogenic aid in participants with excellent aerobic fitness that have optimized other training parameters. Mechanistic research and studies incorporating a wide variety of subjects (e.g., women) are needed to advance the study of NO3 supplementation; however, additional descriptive studies of young, healthy men may have limited utility.


Assuntos
Suplementos Nutricionais , Exercício Físico/fisiologia , Nitratos/administração & dosagem , Substâncias para Melhoria do Desempenho/administração & dosagem , Resistência Física/efeitos dos fármacos , Aptidão Cardiorrespiratória , Esquema de Medicação , Humanos , Inalação , Consumo de Oxigênio , Caracteres Sexuais
13.
Nutrients ; 12(9)2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32971774

RESUMO

To determine the effects of pre-sleep supplementation with a novel low glycemic index (LGI) carbohydrate (CHO) on next-morning substrate utilization, gastrointestinal distress (GID), and endurance running performance (5-km time-trial, TT). Using a double-blind, randomized, placebo (PLA) controlled, crossover design, trained participants (n = 14; 28 ± 9 years, 8/6 male/female, 55 ± 7 mL/kg/min) consumed a LGI, high glycemic index (HGI), or 0 kcal PLA supplement ≥ 2 h after their last meal and <30 min prior to sleep. Upon arrival, resting energy expenditure (REE), substrate utilization, blood glucose, satiety, and GID were assessed. An incremental exercise test (IET) was performed at 55, 65, and 75% peak volume of oxygen consumption (VO2peak) with GID, rating of perceived exertion (RPE) and substrate utilization recorded each stage. Finally, participants completed the 5-km TT. There were no differences in any baseline measure. During IET, CHO utilization tended to be greater with LGI (PLA, 56 ± 11; HGI, 60 ± 14; LGI, 63 ± 14%, p = 0.16, η2 = 0.14). GID was unaffected by supplementation at any point (p > 0.05). Performance was also unaffected by supplement (PLA, 21.6 ± 9.5; HGI, 23.0 ± 7.8; LGI, 24.1 ± 4.5 min, p = 0.94, η2 = 0.01). Pre-sleep CHO supplementation did not affect next-morning resting metabolism, BG, GID, or 5-km TT performance. The trend towards higher CHO utilization during IET after pre-sleep LGI, suggests that such supplementation increases morning CHO availability.


Assuntos
Atletas , Desempenho Atlético/fisiologia , Carboidratos da Dieta/administração & dosagem , Índice Glicêmico , Corrida/fisiologia , Amido/administração & dosagem , Adulto , Glicemia/análise , Estudos Cross-Over , Método Duplo-Cego , Metabolismo Energético/efeitos dos fármacos , Feminino , Humanos , Masculino , Consumo de Oxigênio , Resistência Física/efeitos dos fármacos , Placebos , Saciação , Sono
14.
Nutrients ; 12(9)2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32911636

RESUMO

Much research has been done in sports nutrition in recent years as the demand for performance-enhancing substances increases. Higher intake of nitrates from the diet can increase the bioavailability of nitric oxide (NO) via the nitrate-nitrite-NO pathway. Nevertheless, the increased availability of NO does not always lead to improved performance in some individuals. This review aims to evaluate the relationship between the athlete's training status and the change in time trial performance after increased dietary nitrate intake. Articles indexed by Scopus and PubMed published from 2015 to 2019 were reviewed. Thirteen articles met the eligibility criteria: clinical trial studies on healthy participants with different training status (according to VO2max), conducting time trial tests after dietary nitrate supplementation. The PRISMA guidelines were followed to process the review. We found a statistically significant relationship between VO2max and ergogenicity in time trial performance using one-way ANOVA (p = 0.001) in less-trained athletes (VO2 < 55 mL/kg/min). A strong positive correlation was observed in experimental situations using a chronic supplementation protocol but not in acute protocol situations. In the context of our results and recent histological observations of muscle fibres, there might be a fibre-type specific role in nitric oxide production and, therefore, supplement of ergogenicity.


Assuntos
Atletas , Nitratos/farmacologia , Substâncias para Melhoria do Desempenho/farmacologia , Resistência Física/efeitos dos fármacos , Desempenho Atlético , Bases de Dados Factuais , Suplementos Nutricionais , Humanos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Óxido Nítrico/farmacologia , Consumo de Oxigênio , Fatores de Tempo
15.
Eur J Oncol Nurs ; 48: 101823, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32835999

RESUMO

PURPOSE: Older adults receiving cancer chemotherapy are at increased risk for decrements in physical (PF) and cognitive (CF) function. OBJECTIVES: Study identified subgroups of patients with distinct PF and CF profiles; risk factors associated with subgroup membership; and impact of subgroup membership on quality of life (QOL). METHODS: In 366 older oncology patients, PF and CF were assessed using the Physical Component Summary (PCS) of the SF-12 and Attentional Function Index, respectively. Latent profile analysis was used to identify subgroups of older patients with distinct PF/CF profiles. RESULTS: Three distinct PF/CF profiles were identified (i.e., Very Low PF + Moderate CF (15.6%); Low PF + Low CF (39.3%), Normal PF + Normal CF (45.1%)). Compared to the both Normal class, patients in the other two classes had a lower functional status, a worse comorbidity profile, and were less likely to exercise on a regular basis. Compared to the Both Normal class, patients in the Both Low class were less likely to be married/partnered, more likely to live alone, less likely to be employed, and more likely to report depression and back pain. Compared to the other two classes, patients in the Both Low class had a lower annual household income and were receiving chemotherapy with a worse toxicity profile. CONCLUSION: First study to use a person-centered analytic approach to identify subgroups of older adults with distinct PF/CF profiles. Fifty-five percent of the older adults had statistically significant and clinically meaningful decrements in both PF AND CF that had negative effects on all aspects of QOL.


Assuntos
Antineoplásicos/efeitos adversos , Cognição/efeitos dos fármacos , Comorbidade , Neoplasias/complicações , Neoplasias/tratamento farmacológico , Resistência Física/efeitos dos fármacos , Qualidade de Vida/psicologia , Idoso , Idoso de 80 Anos ou mais , California , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/epidemiologia , Fatores de Risco
16.
PLoS One ; 15(8): e0236592, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790792

RESUMO

Caffeine improves cycling time trial performance through enhanced motor output and muscle recruitment. However, it is unknown if caffeine further increases power output entropy. To investigate the effects of caffeine effects on cycling time trial performance and motor output entropy (MOEn), nine cyclists (VO2MAX of 55 ± 6.1 mL.kg.-1min-1) performed a 4 km cycling time trial (TT4km) after caffeine and placebo ingestion in a counterbalanced order. Power output data were sampled at a 2 Hz frequency, thereafter entropy was estimated on a sliding-window fashion to generate a power output time series. A number of mixed models compared performance and motor output entropy between caffeine and placebo every 25% of the total TT4km distance. Caffeine ingestion improved power output by 8% (p = 0.003) and increased MOEn by 7% (p = 0.018). Cyclists adopted a U-shaped pacing strategy after caffeine ingestion. MOEn mirrored power output responses as an inverted U-shape MOEn during the time trial. Accordingly, a strong inverse correlation was observed between MOEn and power output responses over the last 25% of the TT4km (p < 0.001), regardless of the ingestion, likely reflecting the end spurt during this period (p = 0.016). Caffeine ingestion improved TT4km performance and motor output responses likely due to a greater power output entropy.


Assuntos
Desempenho Atlético , Cafeína/farmacologia , Estimulantes do Sistema Nervoso Central/farmacologia , Resistência Física/efeitos dos fármacos , Adulto , Ciclismo , Entropia , Humanos , Masculino , Efeito Placebo
17.
Nutrients ; 12(8)2020 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-32722588

RESUMO

Dietary nitrate (NO3-) supplementation has been evidenced to induce an ergogenic effect in endurance and sprint-type exercise, which may be underpinned by enhanced muscle contractility and perfusion, particularly in type II muscle fibers. However, limited data are available to evaluate the ergogenic potential of NO3- supplementation during other exercise modalities that mandate type II fiber recruitment, such as weightlifting exercise (i.e., resistance exercise). In this systematic review, we examine the existing evidence basis for NO3- supplementation to improve muscular power, velocity of contraction, and muscular endurance during weightlifting exercise in healthy adults. We also discuss the potential mechanistic bases for any positive effects of NO3- supplementation on resistance exercise performance. Dialnet, Directory of Open Access Journals, Medline, Pubmed, Scielo, Scopus and SPORT Discus databases were searched for articles using the keywords: nitrate or beetroot and supplement or nut*r or diet and strength or "resistance exercise" or "resistance training" or "muscular power". Four articles fulfilling the inclusion criteria were identified. Two of the four studies indicated that NO3- supplementation could increase aspects of upper body weightlifting exercise (i.e., bench press) performance (increases in mean power/velocity of contraction/number of repetitions to failure), whereas another study observed an increase in the number of repetitions to failure during lower limb weightlifting exercise (i.e., back squat). Although these preliminary observations are encouraging, further research is required for the ergogenic potential of NO3- supplementation on weightlifting exercise performance to be determined.


Assuntos
Desempenho Atlético/fisiologia , Suplementos Nutricionais , Nitratos/farmacologia , Substâncias para Melhoria do Desempenho/farmacologia , Levantamento de Peso/fisiologia , Adulto , Voluntários Saudáveis , Humanos , Masculino , Músculo Esquelético/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Treinamento de Força
18.
Nutrients ; 12(7)2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32708555

RESUMO

The present study investigated whether the caffeine supplementation for four days would induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters of cyclists. A double-blind placebo-controlled cross-over design was employed, involving four experimental trials; placebo (4-day)-placebo (acute)/PP, placebo (4-day)-caffeine (acute)/PC, caffeine (4-day)-caffeine (acute)/CC and caffeine (4-day)-placebo (acute)/CP. Fourteen male recreationally-trained cyclists ingested capsules containing either placebo or caffeine (6 mg∙kg-1) for 4 days. On day 5 (acute), capsules containing placebo or caffeine (6 mg∙kg-1) were ingested 60 min before completing a 16 km time-trial (TT). CC and PC showed improvements in time (3.54%, ES = 0.72; 2.53%, ES = 0.51) and in output power (2.85%, ES = 0.25; 2.53%, ES = 0.20) (p < 0.05) compared to CP and PP conditions, respectively. These effects were accompanied by increased heart rate (2.63%, ES = 0.47; 1.99%, ES = 0.34), minute volume (13.11%, ES = 0.61; 16.32%, ES = 0.75), expired O2 fraction (3.29%, ES = 0.96; 2.87, ES = 0.72), lactate blood concentration (immediately after, 29.51% ES = 0.78; 28.21% ES = 0.73 recovery (10 min), 36.01% ES = 0.84; 31.22% ES = 0.81), and reduction in expired CO2 fraction (7.64%, ES = 0.64; 7.75%, ES = 0.56). In conclusion, these results indicate that caffeine, when ingested by cyclists in a dose of 6 mg∙kg-1 for 4 days, does not induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters.


Assuntos
Desempenho Atlético , Ciclismo/fisiologia , Cafeína/administração & dosagem , Cafeína/farmacologia , Suplementos Nutricionais , Substâncias para Melhoria do Desempenho , Resistência Física/efeitos dos fármacos , Fenômenos Fisiológicos da Nutrição Esportiva/fisiologia , Adulto , Glicemia , Cafeína/sangue , Estudos Cross-Over , Método Duplo-Cego , Fadiga/prevenção & controle , Feminino , Humanos , Hidrocortisona/sangue , Lactatos/sangue , Masculino , Fatores de Tempo
19.
Artigo em Inglês | MEDLINE | ID: mdl-32698345

RESUMO

BACKGROUND: Ageing is associated with changes of physical and physiological parameters, but there is evidence that regular physical activity could minimize these effects. Additionally, the older population presents a great risk of suboptimal nutrition. Therefore, the purpose of this study was to review the evidence of nutritional strategies and endurance exercises in the older population. METHODS: A systematic review was performed based on the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement. The search was carried out in three different databases: PubMed, Web of Science, and SPORTDiscus. RESULTS: Eight studies were included in the present review. The use of caffeine and beta-alanine supplementation with proteins have been found to be beneficial in both sexes. In older women, a balanced diet, an increase in protein, supplementation with beta hydroxy methyl butyrate, and supplementation with sodium bicarbonate have been favorable. However, no benefit has been seen in older men with sodium bicarbonate or ubiquinone supplementation. Nevertheless, the use of supplements should be prescribed according to individual characteristics and physical activity. CONCLUSIONS: Caffeine and high protein supplement with beta-alanine may provide positive effects in the older population. In addition, in older women, bicarbonate supplementation and beta-hydroxyethyl butyrate (HMB), lysine, and arginine supplementation have shown positive effects on exercise performance.


Assuntos
Envelhecimento/fisiologia , Cafeína/administração & dosagem , Suplementos Nutricionais/efeitos adversos , Exercício Físico , Resistência Física/efeitos dos fármacos , Idoso , Terapia por Exercício , Feminino , Humanos , Masculino
20.
J Int Soc Sports Nutr ; 17(1): 37, 2020 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-32660566

RESUMO

BACKGROUND: Recent evidence indicates that elevating plasma nitrites through dietary nitrates (NO3-) supplementation is associated with enhanced muscle efficiency, fatigue resistance and performance. Beetroot (in various forms) is the dominant source of dietary NO3- primarily due to its vast availability and the simple form of preparation suitable for final consumption. After a few years of research and experimentation, our scientific team identified alternative source rich with dietary NO3- as possible nitric oxide precursor, amaranth (Amaranthus hypochondriacus) with a standardized concentration 9-11% of NO3-. This study aimed to evaluate the effect of single-dose (±400 mg of dietary NO3-) and long-term (6 days) supplementation of amaranth concentrate derived dietary NO3- on aerobic capacity in physically active young people. METHODS: We conducted a randomized, double-blind, placebo-controlled human study. Thirteen healthy and physically active young male participants were randomized into experimental and placebo groups. The aerobic capacity was tested during increasing cycling exercise (ICE) with pulmonary gas exchange recording and analysis. RESULTS: The peak power of the ICE, the maximum oxygen consumption and the first ventilatory threshold were significantly increased after long-term consumption of dietary amaranth (from 4.44 ± 0.50 to 4.55 ± 0.43 W/kg; from 37.7 ± 2.7 to 41.2 ± 5.4 mL/kg/min and from 178.6 ± 30.3 to 188.6 ± 35.2 W, p < 0.05; respectively) in experimental group. CONCLUSIONS: Long-term (6 days) use of dietary NO3- from amaranth may improve the aerobic capacity during ICE in young physically active male persons. It can be recommended as the nutritional supplement during last week of preparation for competition in endurance events.


Assuntos
Amaranthus , Suplementos Nutricionais , Nitratos/administração & dosagem , Consumo de Oxigênio/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Método Duplo-Cego , Humanos , Masculino , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...